286 University Geological Survey of Kansas. 
Fig. 60. Framing of jig cell grate. 
move beyond the riffles upon the plain portion of the table, 
where they are washed by the stream of clear water, which 
carries the finer particles of silica into the tailings discharge, 
and also carries the minerals down the table in order of their 
specific gravity. Galena is moved but little by the wash 
water, but by the motion of the table is driven toward the 
concentrates box. Iron pyrites are carried farther down the 
table than galena; zinc blende, quartz with mineral at- 
tached and clear sand are carried down in the order named. 
The lines between the various streaks of mineral formed by 
the combined action of the wash water and motion of the 
table are so distinct that it is an easy matter so to adjust the 
table and wash water that the clean sands are run into the 
waste spout, and the quartz with mineral attached into the 
middlings spout, to be automatically returned to the table to 
be retreated, while all the concentrates are directed into the 
concentrates box. 
‘‘This feature of the Wilfley table—the separation of the 
minerals into distinct streaks, is of great value, as by means 
Fig, 62. Cast iron jig screen. 
